Nation's last Senate race being settled Saturday, with Democrat Mary Landrieu the underdog

BATON ROUGE, La. — In the last election of the 2014 midterms, Louisiana voters Saturday decide the political fate of Democratic Sen. Mary Landrieu, who is struggling to win a fourth term against a wave of GOP gains across Southern states.

Republican Rep. Bill Cassidy was the front-runner in the runoff election, after portraying his candidacy as a way for voters to cast another ballot against the policies of President Barack Obama, who is highly unpopular in Louisiana.

If Cassidy is successful, his win would add a ninth Senate seat pickup for the GOP, pushing their new majority to 54 seats in January and costing Democrats their last Senate seat in the Deep South.

Polls officially closed at 8 p.m. local time.

Landrieu, 59, whose family has been a New Orleans political dynasty, fought throughout her campaign to make the election a referendum on her own performance rather than on the president. But her votes for Obama's signature health care overhaul and other policies supported by the president were hammered by Cassidy, who repeatedly said the Democratic incumbent voted with Obama "97 percent of the time."

Cassidy, 57, a Baton Rouge doctor, stuck to the near-singular message, after it worked for Republicans who ousted Democratic incumbents earlier this year in North Carolina, Arkansas and Alaska. He spent little time on the campaign trail in the runoff, as his campaign sought to keep him from making any missteps, while Landrieu crisscrossed the state in appearances as she tried to hang onto her job.

Cassidy skipped public events in advance of his post-election party. But as voters went to the polls, Landrieu stood street-side in New Orleans, smiling and waving to motorists as about a dozen supporters danced and waved signs.

She added that she hoped voters cast ballots for a senator who has "delivered for this region time and time again."

But attempts by Landrieu's campaign to respond to the Cassidy criticism and shape a different focus for the runoff were undermined by national Democrats' near total abandonment of the senator. Of every dollar spent by outside groups since Louisiana's Senate race headed into its final month, 97 cents were paid to help Cassidy.

Landrieu was largely left to fend for herself, with assistance from individual colleagues and the state Democratic Party as her only boost.

Her party's lackluster performance nationally on Nov. 4 undermined the central theme of Landrieu's campaign, that her clout was invaluable to Louisiana. With Republicans gaining control of the Senate in the new year, Landrieu would lose her energy committee chairmanship.

A last-ditch attempt to show that she could break through congressional gridlock and pass the long-delayed Keystone XL pipeline fell one vote short of the support she needed from her own party to pass, dealing another blow to Landrieu's campaign narrative.

In the final days, Landrieu centered her criticism on Cassidy's work as a doctor for the LSU hospital system that cares for the poor and uninsured. She said Cassidy appeared to have been paid a $20,000 taxpayer-funded annual salary for doing little or no work, and she suggested he falsified the few timesheets that LSU had produced for the congressman's work. Cassidy tossed aside the criticism as a desperate attempt to revive Landrieu's faltering campaign and said he did nothing wrong.